Yesterday’s VTP question generated a few comments, several with varying answers. One might think that whether VTP should be on the exams these days or not, it’s certainly a topic that is on several Cisco exams, so it’s practical to go ahead and remember the details.
One of the biggest problems with being ready for VTP on the exams is that a lot of people just turn it off (aka use transparent mode) as a matter of habit, so to be ready; most people’s VTP knowledge comes from books, web pages, Cisco documents, and courses. However, today’s blog gets to the root of a VTP behavior that contradicts several descriptions of how VTP works.
I think it’d be very interesting to see where those of us watching this blog think about VTP in regards to the issue of whether a VTP client can cause a VTP server to update its VLAN database. So, I’m going to offer a variation of yesterday’s question, with just two switches, and then ask you to answer the poll – based on what you thought to be true before reading any of this week’s blog comments, both mine and from the rest of the group. My goal here is to see what we believed to be true, and then I’ll discuss what really happens in my next blog entry.
Let’s say SW1 and SW4 are not connected to each other. They both use the same VTP domain name and same password, so their MD5 digests on the show vtp status command are identical. They both know about the default VLANs (1, 1002-1005). The difference is that SW1 has VLAN 11 configured, and has VTP revision number 2, while SW4 has VLAN 44 configured, with VTP revision number 8. (Essentially, this is a subset of Monday’s question, except that the passwords match.) Then, the two switches connect to each other via a trunk. What happens?
What I’m after in this survey is not what you believe today, but what you believed before reading the last few days in this blog. I think it’ll be interesting to any of us who care to be ready for VTP questions to see where people sit on this behavior. So, with all that background, here’s the poll:
More tomorrow, or Thursday – I’m scheduled to take the CCDE written beta tomorrow, so I’ll let you know my impressions from that as well before the weeks out.
